1. Field of the Invention
This invention relates to a chair, in particular an office chair, comprising a seat and a back rest which are pivotable with respect to the column that supports them.
2. Description of the Prior Art
Many forms of chairs of the before-mentioned type are known. In addition to a purely elevational adjustment, they also permit pivoting of the seat and the back rest about horizontal, transversely directed axes so that the chair can be adjusted to different sitting positions of the user, for example, a straight, erect, working position or a leaning-back, resting position.
Conventional chair constructions of this type employ springs which resiliently resist pivoting of the seat and back rest, caused by the weight of the user or by a force applied by the user, and resiliently urge the chair into a selected, initial position. These springs represent a not-insignificant portion of the total manufacturing cost of the chair because they are made of high-quality materials, they must be carefully anchored and, taking into consideration the requisite spring deflection, they may require a considerable amount of space. A further structural disadvantage is that the extent of spring deflection varies with chair occupants of different weights. To provide a spring behavior which is substantially independent of the load requires at least a relatively complicated and expensive adjusting mechanism.